One of the visual motifs of the stark and shocking Lao Shi (Old Stone) is a cigarette burning in the dark. As the movie's taxi-driving protagonist inhales, the tip pulses red like a warning beacon. It signals danger on the road.
The hazard is explained casually in the opening scene, in which Lao Shi (Chen Gang) waits while listening to a radio report about a driver who hit someone, but didn't kill him. Rather than be responsible for the victim's medical costs, the driver backed up and ran over him. In China, life can be cheaper than hospital bills.